For elevator systems, steel cables have traditionally been used as suspension means for carrying and/or driving an elevator car. According to a further development of such steel cables, belt-like suspension means are used that have tension members and a sheathing arranged around the tension members. However, such belt-like suspension means cannot be monitored in the traditional manner because the tension members, which determine the breaking load of the suspension means, are not visible through the sheathing.
To monitor such tension members in belt-like suspension means, a test current can be applied to the tension members. In the circuit configured in this way, a current flow or a current strength, a voltage, an electrical resistance or an electrical conductivity is measured. It is possible to draw a conclusion about the intactness of the tension members of the suspension means based on a quantity measured in this way.
Publication DE 3934654 A1 discloses such a device or such a method for the determination of a state of the tension members of a belt-like suspension means. Using a circuit in which all tension members of the suspension means are connected in series, it can be easily determined whether at least one of the tension members is broken or not.
Although one such monitoring method described in the prior art is reliable in the monitoring of breakages of tension members, no other damage to the suspension means can be determined with it.